It's almost always...
...A tortilla with meat, cheese and lettuce.
No, seriously.
What is a taco? A tortilla with meat, cheese and lettuce.
What is a burrtio? A tortilla with meat, cheese and lettuce.
What is a fajita? A tortilla with meat, cheese and lettuce.
What are nachos? Little tortillas with meat, cheese and lettuce.
But seriously.
Mexican food is
food from Mexico.
And it's good.
:D